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Biomedical subjects

C Puchstein

Publications and source records attributed to C Puchstein.

33 records · Page 2Linked to original sources
PubMed1983

Treatment of hypertension with labetalol in neurosurgical practice. Influence of labetalol on cerebral perfusion pressure in dogs without and with intracranial mass lesions.

In neurosurgical patients autoregulation of cerebral perfusion is often lost. Therefore, a sudden increase in blood pressure may lead to an increase in cerebral blood flow and cerebral oedema may follow. The influence of labetalol, a new alpha- and beta-adrenoceptor blocking agent, on intracranial pressure and cerebral perfusion pressure was investigated in dogs without and with mass lesions. During hypotension with labetalol the intracranial pressure remained unchanged and the cerebral perfusion pressure decreased to the same extent as mean arterial pressure (30%). Labetalol seems to be suitable to treat hypertension perioperatively in neurosurgical patients but it is not a suitable drug for induced hypotension.

Animals↗
PubMed1983

The influence of urapidil, a new antihypertensive agent, on cerebral perfusion pressure in dogs with and without intracranial hypertension.

The influence of urapidil, an arylpiperazinederivate, on intracranial pressure (ICP), mean arterial pressure (MAP) and cerebral perfusion pressure (CPP) was investigated in dogs with (group II) and without (group I) intracranial hypertension. After i.v. administration of urapidil, intracranial pressure remained unchanged and cerebral perfusion pressure decreased to the same extent as mean arterial pressure (20%). As in neurosurgical patients, autoregulation of cerebral blood flow is often lost; a sudden increase in blood pressure may lead to an increase in cerebral blood flow and to a damage of the blood bain barrier with consequent cerebral edema. Urapidil seems to be suitable for treating hypertensive episodes perioperatively in neurosurgical patients.

Anesthesia, Conduction↗
PubMed1983

Influence of urapidil on intracranial pressure and intracranial compliance in dogs.

During induced hypotension with urapidil, measurements of intracranial pressure and of the ventricular volume-pressure response (intracranial compliance) were obtained in dogs with and without intracranial hypertension. A bolus of urapidil 50 mg plus an infusion of urapidil 8.2 +/- 1.2 mg min-1 decreased mean arterial pressure by 22 +/- 10% from control in group I (without intracranial hypertension) and by 24 +/- 8% in group II (with intracranial hypertension). In both groups there was no change in intracranial pressure or in intracranial compliance after the administration of urapidil.

Animals↗
PubMed1982

Effect of labetalol on intracranial pressure in dogs with and without intracranial hypertension.

Intracranial pressure measurements and ventricular volume pressure response curves were made during induced hypotension with labetalol, a combined alpha- and beta-adrenoceptor antagonist, in dogs without (group I) and with (group II) intracranial hypertension. The administration of 600 mg labetalol resulted in a percentage decrease of mean systemic arterial blood pressure (MAP) of 27% (+/- 10%) in group I, and 32% (+/- 9%) in group II from control values without changes in intracranial pressure and the ventricular volume pressure response curve. Larger decreases in MAP were not possible, even with a dose 3 times that clinically recommended. Labetalol may be a safe hypotensive agent to supplement neurolept analgesia, but it is not the drug of choice to induce deliberate hypotension.

Animals↗
PubMed1982

The use of labetalol in producing deliberate hypotension and its effects on intracranial pressure in dogs.

The use of effective and safe hypotensive agents in neuroanesthesia is a difficult and unanswered question. Most hypotensive agents produce an increase in intracranial pressure and as a result can not be used until the dura is opened. In experiments in dogs, Labetalol, a combined alpha and beta-adrenoceptor antagonist, showed no increase in intracranial pressure and no change in intracranial compliance by producing hypotension.

Anesthesia↗
PubMed1982

[Controlled hypotension with ATP. Animal experiment studies in dogs].

Reliable efficacy and short half-time, combined with the absence of tachyphylaxis and reactive hypertension during and after controlled hypotension should be considered important factors in the use of hypotensive drugs. The vasodilating action of adenosine triphosphate (ATP) was investigated for deliberate hypotension in anaesthesized dogs. During a continuous infusion, in which the dose of ATP was increased from 1 mg/kg . min ATP to 5 mg/kg . min ATP, a stepwise decrease in mean arterial pressure (MAP) and systemic vascular resistance (SVR) could be observed (55%; p less than 0.001). Cardiac output and heart rate increased (p less than 0.05). The physiological intrapulmonary shunt remained unchanged during ATP infusion. ATP acts within 30 sec. and after the end of the infusion haemodynamic parameters returned to control levels within two minutes.

Adenosine Triphosphate↗
PubMed1979

Specific binding of 3H-adenosine to rat brain membranes.

The binding of 3H-adenosine to rat brain membranes was studied by a microcentrifugation technique. Specific binding of 3H-adenosine was rapid, reversible, saturable and dependent on pH and temperature. Scatchard plots of equilibrium binding data were nonlinear suggesting the existence of two different binding sites for adenosine. The dissociation constants (Kd) were 1.7 muM and 13.6 muM and the maximal number of binding sites (Bmax) 31 and 165 pmol adenosine bound per mg of membrane protein. Ten adenosine derivatives were studied for their ability to compete with 3H-adenosine binding. The phosphorylated adenosine compounds 5'-AMP, cyclic AMP and ATP were most potent in displacing 3H-adenosine from its binding sites and the IC50-values ranged from 11--25 muM. N6-Phenylisopropyladenosine produced only partial inhibition (30%) of 3H-adenosine binding and no stereospecific difference between the (-)- and (+)isomer was observed. Several methylxanthines known as adenosine antagonists competed for the 3H-adenosine binding sites parallel with their pharmacological potency. The results offer a first approach for the study of adenosine binding sites in brain membranes.

Adenosine↗
PubMedDate not supplied

Plasma and muscle carnitine in healthy and hemodialyzed children.

Total carnitine and its subfractions (free carnitine, short-chain and long-chain acylcarnitine) have been measured in plasma and muscle of healthy children of both sexes aged 0.1-18 years using a modified radiochemical-enzymatic assay. Up to the age of 9 years, no differences were apparent between boys and girls while in the range of 10-18 years the boys revealed increased and girls similar concentrations of free and total plasma carnitine compared to the younger children. Plasma concentrations of total and free carnitine revealed weak, but significant correlations with age in boys and girls, while muscle concentrations of total carnitine and its subfractions were not age dependent. No correlations were apparent between any of the plasma and muscle carnitine fractions. Plasma carnitine concentrations measured in hemodialyzed children showed a disturbed pattern of the fractions, whereas muscle concentrations were apparently normal in these patients. The present study provides reference values of free carnitine and the acylcarnitines in plasma and muscle of healthy children and emphasizes the necessity to use appropriate reference values for assessing carnitine metabolism in pediatric patients.

Carnitine↗